William Delgado, 28, also pleaded guilty to assault and battery with a dangerous weapon. He must serve a three- to five-year state prison term and an additional five years' probation which must include anger management counseling.

A prosecutor told Judge Mary Lou Rup in Hampden Superior Court that the victim thought Delgado was his friend and was shocked at the February assault. The victim suffered two large, permanent scars to his head, according to assistant District Attorney Karen Southerland.

Defense lawyer Daniel R. Bergin said Delgado surrendered to police several hours after the attack. He said Delgado had been abusing drugs and having a "severe mental defect" at the time of the attack, and his memory about that day is vague.